Power supply



FIG. 1 is a front view of a power supply showing my new design;

FIG. 2 is a left view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a bottom view thereof;

FIG. 6 is a bottom perspective view thereof; and,

FIG. 7 is a top perspective view thereof. 

The ornamental design for a power supply, as shown and described. 